1. Field of the Invention
The present invention is related to a manufacturing method of skis used for winter sports and adapted to slide on snow and ice, such as alpine skis, mono-skis, and snowboards.
2. Discussion of Background and Relevant Information
Currently known skis generally have a composite structure in which different materials are combined in such a way that each of them cooperates in the structure in an optimal manner, in view of the distribution of mechanical stresses. Thus, the structure generally comprises peripheral decorative and protective elements, forming the upper surface and the lateral surfaces of the ski, internal resistance elements or resistance blades, constituted of a material having substantial mechanical resistance and substantial stiffness. The structure also comprises filler elements such as a core having an alveolar structure, a sliding sole forming the lower surface of the ski and ensuring good sliding on snow, and metallic running edges forming the lower edges of the ski.
In order to obtain the appropriate physical characteristics, modern ski manufacturing techniques use of very diverse materials. For example the sliding soles are generally made of polyethylene, the alveolar cores are made of synthetic foam, the running edges are made of steel, the upper surfaces of the ski are made of thermoplastic films, the resistance blades are metallic or fiber reinforced resin plates.
A ski is subject to severe mechanical stresses, requiring a good adherence between the various materials constituting the structure. In traditional ski manufacturing techniques, the cores are prefabricated in their definitive configuration by machining. They are then subjected to a surface treatment by sanding or punching so as to be able to adhere with the adhesive constituting the matrix of the internal resistance elements, generally of the epoxy type. The assembly of the core with the other elements of the ski is generally done during a later molding step.
The core of a ski is an essential element because it contributes to rigidity in flexion and ensures a filling of the gaps between the various upper, lower and lateral internal resistance elements. The shapes of modern skis have also changed considerably to enable an improvement in the quality of behavior, sliding, or simply an improvement in aesthetic characteristics of view. This is how, skis having inclined, convex or concave lateral edges have appeared, or even skis having corrugations on their upper surface, etc. Thus, the shape of the cores has changed with these new shapes of skis and traditional manufacturing methods comprising machining and surface preparation steps have now become ill-adapted, expensive and complex. In addition, their implementation also leads to numerous problems. In particular, the machining step destroys the fine surface layer of greater density of the synthetic cores (known as the "skin" of the core by specialists). Also, the geometry cannot be reproduced from one core to another.